From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v7 0/9] ARM: VDSO
Date: Tue, 1 Jul 2014 10:04:29 +0100 [thread overview]
Message-ID: <20140701090429.GD28164@arm.com> (raw)
In-Reply-To: <53B1DD21.6020709@mit.edu>
On Mon, Jun 30, 2014 at 10:56:49PM +0100, Andy Lutomirski wrote:
> On 06/30/2014 08:42 AM, Nathan Lynch wrote:
> > On 06/30/2014 09:40 AM, Will Deacon wrote:
> >> - If we use your code to build an arm64 vdso, how much slower is it than
> >> the handcrafted asm we currently have?
> >
> > Someone with access to 64-bit hardware (i.e. not me) would have to find
> > this out, but I would not be surprised if the C code could be tightened
> > up -- I have not spent much time on optimizing it.
> >
>
> I can't comment on ARM specifically, but the only assembly in the x86
> vclock_gettime is an asm volatile (""), which causes gcc to emit more
> optimal code. I doubt I could shave off more than a cycle or two by
> rewriting it in assembly.
The arm64 version avoids the stack completely (we have lots of registers),
so I'd expect a significant win over a C version. However, I'd be interested
to see a comparison as the C version is clearly more maintainable.
Will
prev parent reply other threads:[~2014-07-01 9:04 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 3:11 [PATCH v7 0/9] ARM: VDSO Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 1/9] clocksource: arm_arch_timer: change clocksource name if CP15 unavailable Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 2/9] clocksource: arm_arch_timer: enable counter access for 32-bit ARM Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 3/9] ARM: arch_timer: remove unused functions Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 4/9] arm64: " Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 5/9] ARM: place sigpage at a random offset above stack Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 6/9] ARM: miscellaneous vdso infrastructure, preparation Nathan Lynch
2014-06-30 10:11 ` Arnd Bergmann
2014-06-30 12:27 ` Nathan Lynch
2014-06-30 13:06 ` Arnd Bergmann
2014-06-23 3:11 ` [PATCH v7 7/9] ARM: add vdso user-space code Nathan Lynch
2014-06-28 9:53 ` Russell King - ARM Linux
2014-06-28 10:03 ` Russell King - ARM Linux
2014-06-30 15:56 ` Andy Lutomirski
2014-06-28 15:19 ` Nathan Lynch
2014-06-28 15:26 ` Russell King - ARM Linux
2014-06-28 16:13 ` Nathan Lynch
2014-06-28 18:12 ` Russell King - ARM Linux
2014-06-28 19:45 ` Nathan Lynch
2014-06-28 20:11 ` Russell King - ARM Linux
2014-06-28 21:35 ` Nathan Lynch
2014-06-29 8:34 ` Russell King - ARM Linux
2014-06-29 15:48 ` Nathan Lynch
2014-06-29 16:07 ` Russell King - ARM Linux
2014-06-29 23:04 ` Nathan Lynch
2014-06-30 21:33 ` Andy Lutomirski
2014-06-30 15:59 ` Andy Lutomirski
2014-06-30 16:50 ` Nathan Lynch
2014-06-30 21:29 ` Andy Lutomirski
2014-07-01 9:00 ` Will Deacon
2014-07-01 13:34 ` Nathan Lynch
2014-07-01 14:11 ` Andy Lutomirski
2014-07-01 13:28 ` Nathan Lynch
2014-07-01 14:56 ` Andy Lutomirski
2014-06-23 3:11 ` [PATCH v7 8/9] ARM: vdso initialization, mapping, and synchronization Nathan Lynch
2014-06-30 21:37 ` Andy Lutomirski
2014-07-01 9:03 ` Will Deacon
2014-07-01 14:11 ` Nathan Lynch
2014-07-01 14:15 ` Will Deacon
2014-07-01 14:17 ` Andy Lutomirski
2014-07-01 17:27 ` Christopher Covington
2014-07-02 14:40 ` Will Deacon
2014-07-02 15:54 ` Andy Lutomirski
2014-07-02 16:18 ` Nathan Lynch
2014-07-02 16:27 ` Will Deacon
2014-07-02 16:47 ` Andy Lutomirski
2014-07-02 17:24 ` Will Deacon
2014-07-02 18:34 ` Andy Lutomirski
2014-07-02 18:54 ` Will Deacon
2014-07-22 0:14 ` Andy Lutomirski
2014-07-22 8:13 ` Will Deacon
2014-07-01 14:01 ` Nathan Lynch
2014-07-01 14:09 ` Andy Lutomirski
2014-07-01 14:14 ` Russell King - ARM Linux
2014-06-23 3:11 ` [PATCH v7 9/9] ARM: add CONFIG_VDSO Kconfig and Makefile bits Nathan Lynch
2014-06-27 8:51 ` [PATCH v7 0/9] ARM: VDSO Jan Glauber
2014-06-27 8:57 ` Russell King - ARM Linux
2014-06-27 9:41 ` Ard Biesheuvel
2014-06-27 9:46 ` Russell King - ARM Linux
2014-06-27 17:01 ` Nathan Lynch
2014-06-28 9:42 ` Russell King - ARM Linux
2014-06-28 9:55 ` Russell King - ARM Linux
2014-06-28 14:49 ` Russell King - ARM Linux
2014-06-30 7:27 ` Arnd Bergmann
2014-06-30 7:43 ` Arnd Bergmann
2014-06-30 18:27 ` Nathan Lynch
2014-06-27 16:00 ` Nathan Lynch
2014-06-30 16:03 ` Andy Lutomirski
2014-06-30 8:12 ` Ard Biesheuvel
2014-07-01 16:34 ` Nathan Lynch
2014-07-01 20:08 ` Ard Biesheuvel
2014-07-01 22:44 ` Russell King - ARM Linux
2014-06-30 14:40 ` Will Deacon
2014-06-30 15:42 ` Nathan Lynch
2014-06-30 21:56 ` Andy Lutomirski
2014-07-01 9:04 ` Will Deacon [this message]
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